1. Field of the Invention
The present invention relates generally to a method and structure for monitoring polysilicon gate defects. More particularly, the subject invention pertains to a method and structure for monitoring polysilicon gate defects in a semiconductor device by providing the semiconductor device with an electron-generating photodiode region to be used as a circuit stimulus in response to incident light, and also with conductive paths connecting the photodiode electron-generating region to terminals of the polysilicon gate areas. The photodiode region of the semiconductor device is illuminated with light to stimulate the semiconductor device, and light is detected which is emitted therefrom.
2. Discussion of the Prior Art
Currently, test probing of polysilicon lines on silicon chips is performed with mechanical test probes. The mechanical test probes frequently break off chips of polysilicon, which then often short adjacent polysilicon lines.
It is a primary object of the present invention to provide a method and structure for monitoring polysilicon gate defects.
A further object of the subject invention is the provision of a method and structure for monitoring polysilicon gate defects which provides:
early defect monitor testing during the manufacture of integrated circuits;
a low cost testing method utilized during the manufacture of integrated circuits;
an elimination of defects caused by physical contact of mechanical test probes during defect monitor testing;
a reduction in additional manufacturing process steps to account for physical test probing;
In accordance with the teachings herein, the present invention provides a method of detecting defects in a semiconductor device by providing the semiconductor device with an electron-generating photodiode region to be used as a circuit stimulus in response to incident light, illuminating the photodiode region of the semiconductor device with light to stimulate the semiconductor device, and detecting light emitted therefrom.
In greater detail, the semiconductor device is illuminated with light at a first wavelength, and light is detected emitted by the semiconductor device at a second wavelength, different from the first wavelength. The detected light emitted by the illuminated semiconductor device is filtered to remove light at the first wavelength.
The semiconductor device comprises a silicon chip, particularly a polysilicon gated field effect transistor silicon chip, and the photodiode electron-generating region comprises a diffused region in the silicon chip. Moreover, light is detected which is emitted from polysilicon gate areas of the silicon chip. The silicon chip is also provided with conductive paths connecting the photodiode electron-generating region to terminals of the polysilicon gate areas, although some embodiments of the present invention may not require such conductive paths.
The photodiode region is illuminated with a laser beam, and the power of the laser beam can be selectively varied to provide multiple images under different test conditions.
An image is formed of light emitted by the semiconductor device, and the image is captured and analyzed in a computer having a frame acquisition capability.